writes texture (varianceMap[4]) whose usage (0x01) doesn't specify MTLTextureUsageShaderWrite (0x02)

[ukman]

I started the app and I fixed the problem #3 but now I have the following error:

validateComputeFunctionArguments:860: failed assertion `Compute Function(haarCascadePixelParallelFromTexture): writes texture (varianceMap[4]) whose usage (0x01) doesn't specify MTLTextureUsageShaderWrite (0x02)'

It occurs in line https://github.com/christopherhelf/iOS-Metal-HaarCascade/blob/master/iOS-HaarCascade-Improved/MetalComputeShader.swift#L174

[christopherhelf]

That requirement is new as well: for textures that are written into/read from, you need to specify the usage flags in the MTLTextureDescriptor object that is used to create the texture like

descriptor.usage = [.shaderRead, .shaderWrite]

[YongilChoi]

             let outputTextureDescriptor = MTLTextureDescriptor.texture2DDescriptor(pixelFormat: .rgba8Unorm,
                                                                                           width: inputTexture.width,
                                                                                           height: inputTexture.height,
                                                                                           mipmapped: false)
                    outputTextureDescriptor.usage = [.shaderRead, .shaderWrite]